1. Field of the Invention
This invention relates generally to the field of flexible tracks and, more particularly, to a flexible track and carriage system for guiding and supporting a tool, such as a welding or cutting machine, along a work surface.
2. Description of the Prior Art
Track systems are known in the art for guiding a welding or cutting machine on a work surface. Such track systems are used in many industrial areas, such as structural steel work, machinery manufacture and repair, ship building and ship repair, containment vessels, tubing, conductors, etc. In some cases, a rigid track or rail system is used. However, in many cases, a flexible rail system is advantageous to allow the welding or cutting machine to traverse a non-planar i.e., curved work surface. A flexible rail system allows the rail to be used over straight as well as curved surfaces.
One example of such a prior track system is disclosed in U.S. Pat. No. 4,570,542 to Cable et al., which is herein incorporated by reference. In the Cable patent, a band of corrugated sheet metal is attached to the top of a track base. The corrugations of the band form a rack having vertically oriented teeth. The large, vertically oriented drive gear of a welding or cutting machine is configured to engage the vertically oriented teeth of the corrugated band to move the machine along the rack. Since the corrugated band forming the teeth must be able to flex with the track to conform to the shape of the work surface, the thickness of the band, and hence the thickness of the teeth, must necessarily be limited to permit such flexibility. This limits the amount of force which can be applied to the teeth and hence the load which the track is capable of directing. Such vertically oriented, unitary track systems are generally capable of supporting and directing loads only on the order of about 30 pounds. Additionally, the use of a large, vertically oriented gear wheel having an axis of rotation parallel to the top of the track makes the design of a drive system awkward and cumbersome.
Another track system is disclosed in U.S. Pat. No. 5,070,792 to Harris. In the Harris system, a flexible track having a series of perforations is used with a carriage having a large, vertically oriented drive sprocket. The drive sprocket is studded about its periphery with spherical members adapted to mesh with the track perforations. While the Harris system is capable of carrying relatively heavier loads than the cable system discussed above, a problem with the Harris system is that the Harris drive system inherently produces non-uniform, ripple-like motion of the carriage. Such non-uniform motion is detrimental to smooth operation of the tool mounted on the carriage. Also, as with the Cable system described above, the use of a large, vertically oriented drive sprocket tends to make the drive system rather unwieldy.
Therefore, it is an object of the invention to provide a flexible track system which reduces the amount of tooth deformation when the track is conformed to a non-planar work surface. It is additionally an object of the invention to provide a track having a rack structure capable of supporting and directing heavy loads without adversely impacting upon the flexibility of the track. It is also an object of the invention to provide a carriage assembly for supporting a tool, such as a welding or cutting device, which is capable of being quickly and easily attached to or removed from the track system. It is further an object of the invention to provide a track system having a rack profile which permits substantially uniform motion of a supported carriage on straight as well as on curved surfaces.
A track and carriage system is provided for moving a work piece along a flexible track. The system includes a track having at least one track segment, the track segment including a rack assembly formed by a plurality of spaced rack members mounted on the track segment. A carriage assembly is configured to move along the track. The carriage assembly preferably includes a first carriage and a second carriage, which may be removably mounted on the track. A link assembly extends between the two carriages to connect the two carriages as they move along the track. Additional carriages may be connected to the first or second carriages by additional link assemblies.